Application of bipolar electrochemistry to follow electrochemical reactions at the semiconductor-electrolyte interface

Abstract

The properties of metallic minerals and metallic minerals-electrolyte interface have always been a concern in the induced polarization (IP) geophysical method due to their effects on the IP response. Electrochemical reactions, if carried out, affect the interface characteristics. Hence, the occurrence of the reactions and their effects on the IP signal have been modeled through recent research, but they are not well-known yet. Identifying these matters can help to create more realistic physical and petrophysical models, for a better explanation of IP effects. So, in the present study, 11 metallic mineral samples and the laboratory method named bipolar electrochemistry, introduced for the first time to the IP research field, have been used to show the performance of electrochemical reactions at the interface and the effect of various metallic minerals on them. The results showed that if the applied external electric potential is high enough, electrochemical reactions are carried out at the metallic minerals-electrolyte interface. In this study, these reactions were electrolysis of water and were carried out in all minerals (except sphalerite). However, the potential required to initiate the reactions was different for different minerals. The lack of water electrolysis reaction on the surface of sphalerite can probably be attributed to its non-conductivity. On the other hand, the external potential responsible for the interface reactions was linearly linked to the potential difference between the two sample’s extremities. Considering the different potentials required to start the reactions in various samples-electrolyte interfaces, and the absence of these reactions in the case of sphalerite samples, it can be concluded that the samples’ compounds affect the reactions and their commencing potentials. So, we believe that by studying these reactions, some properties of the metallic minerals can be achieved. Identifying the minerals’ properties and the reactions that can occur at their surfaces is essential for a detailed understanding of the factors affecting the IP phenomenon. To do this, we found bipolar electrochemistry as an appropriate way.

Keywords

• bipolar electrochemistry
• induced polarization
• redox reactions
• sulfide minerals